This invention relates to wall board tapes, including dry wall tapes, and particularly relates to a novel wall board plastic tape having fibrous surface to which wall board compound can readily be adhered in substantial thickness in a single coat without fear of the compound cracking or spalling. The tape is specifically applicable to corner joints as well as flat joints and, in one form, is usable on curved joints, such as curved or arched openings, and on the inside or outside tangent corner of a two barrel ceiling. The tape has a fibrous surface coating on both top and bottom sides which attaches to the drywall or wall board setting compound and adheres the tape to the underlying wallboard surface.
Present plastic and paper wall board tapes have certain drawbacks. Water based dry wall or wall board setting compound is difficult to adhere permanently to plastic tapes because plastic products have a smooth surface and some plastics can leak out plasticizers over time which tends to break down the bond between the compound and the tape. To create a mechanical bond, the tape must be roughened or perforations made in the tape to help the adherence problem. As the compound is curing, it sags or oozes from the perforations and drys as a protrusion on the surface. These protrusions make the application of a very thin second coat extremely difficult. These procedures also are costly and/or time consuming.
A difficulty with paper tape is that it tends to absorb water and soften when applied over thick amounts of compound as is necessary when taping irregular joints and corners. When the paper softens it sages and deforms, and a straight line corner is not achieved. Thus, paper must be applied over thin layers of compound which requires a number of coats of compound or the imperfections must be pre-filled, increasing labor costs and time of finishing.
A principal object of the present invention is to provide a plastic tape which can be adhered by water based #1 taping compound in a one coat application to an inside corner or over a two coat application when applied to an outside corner to provide a permanent straight corner. This is achieved without using any mechanical fasteners. When taping an inside corner, dry wall compound is applied to the wallboard surfaces at the corner, the tape is applied and wiped smooth with a taping knife to embed the tape into the compound and remove excess compound, and a finish coat of compound is applied over both wings of the tape and struck off in a finish coat. The fibers on the tape act to center the tape and act as shims to keep tape parallel with the wall surface when the taper bears down on the tape while wiping the tape clean.
Another object is to provide a plastic tape having an embossed raised center portion witch a straight edge to facilitate creasing in a straight line so as to define a straight corner when applied to a corner joint. Still another object is to provide a plastic tape with a raised center and depending wings which are coated on both surfaces with fibers to enhance adherence of water based dry wall compound to the tape. Another object is to provide a flat joint tape with fibers on the surfaces. A further object is to provide a method of making such tapes.
These and other objects and advantages will become apparent hereinafter.